Interactions of chromatic components on the perceptual quantization of the achromatic component

In the human color vision, it is well admitted that signals issued from the three types of receptors (L, M, S) are combined in two opponent color components and one achromatic component. In this paper, we are concerned by the cardinal directions A, Cr1 and Cr2 defined by Krauskopf(1). We study in particular the interactions between luminance and chromatic components. These interactions should be taken into account in visual coding since they modify the visibility thresholds. We present here results that show the influence of the two chromatic components on the optimal perceptual quantizer of the achromatic component in particular subbands. On the subband called III-1 of luminance (radial selectivity 5.7 cy/d degrees to 14.1 cy/d degrees, angular selectivity -15 d degrees to 15 d degrees), we show influence of Cr1 and Cr2 sinusoidal maskers. Others results are also presented on the subband called II-1 (radial selectivity 1,5 cy/d degrees to 5,7 cy/d degrees, angular selectivity -22.5 d degrees to 22.5 d degrees) with Cr1 and Cr2 maskers.